Nearly 1 in 5 adolescents has suffered at least one concussion, a survey of teens finds. Of those, 5.5 percent of them reported two or more concussions diagnosed in their lifetimes, researchers report in the September 26 JAMA.

About 13,000 eighth-, 10th- and 12th-graders took part in the 2016 Monitoring the Future survey, an annual national survey of adolescent behavior and health given in schools. Among other questions, teens were asked whether they had ever had a head injury that was diagnosed as a concussion — 19.5 percent had. Those teens were more likely to participate in competitive sports and be male, white and in a higher grade.

While past studies have found that kids taking part in contact sports have a higher risk of suffering a concussion, the authors of the new study note that data are lacking on how many U.S. adolescents have had concussions, information that’s vital to prevention efforts.